U.S. patent application number 17/164148 was filed with the patent office on 2021-12-30 for oxygen scavenging molecules, articles containing same, and methods of their use.
The applicant listed for this patent is Plastipak Packaging, Inc.. Invention is credited to Girish Nilkanth Deshpande, Michael W. Ensley, Paul David Weipert.
Application Number | 20210403423 17/164148 |
Document ID | / |
Family ID | 1000005828106 |
Filed Date | 2021-12-30 |
United States Patent
Application |
20210403423 |
Kind Code |
A1 |
Deshpande; Girish Nilkanth ;
et al. |
December 30, 2021 |
OXYGEN SCAVENGING MOLECULES, ARTICLES CONTAINING SAME, AND METHODS
OF THEIR USE
Abstract
The invention relates to compounds of the structure of formula I
and II: ##STR00001## where X is selected from the group consisting
of O, S and NH; Y, A and B are independently selected from the
group consisting of N and CH; D, E and F are independently selected
from the group consisting of CH, N, O and S; the symbol ----
represents a single or a double bond; and R.sub.1, R.sub.2 and
R.sub.3 are independently selected from the group consisting of H,
electron withdrawing groups and electron releasing groups. In other
embodiments, the compounds are used as oxygen scavengers and in
barrier compositions and articles.
Inventors: |
Deshpande; Girish Nilkanth;
(Morris Plains, NJ) ; Weipert; Paul David; (High
Point, NC) ; Ensley; Michael W.; (Eden, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Plastipak Packaging, Inc. |
Plymouth |
MI |
US |
|
|
Family ID: |
1000005828106 |
Appl. No.: |
17/164148 |
Filed: |
February 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16189363 |
Nov 13, 2018 |
10906870 |
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17164148 |
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15147532 |
May 5, 2016 |
10125096 |
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16189363 |
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13849797 |
Mar 25, 2013 |
9475630 |
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15147532 |
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13164477 |
Jun 20, 2011 |
8431721 |
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13849797 |
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12117849 |
May 9, 2008 |
7994245 |
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13164477 |
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60928553 |
May 10, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 20/262 20130101;
B65D 65/38 20130101; C07D 471/04 20130101; C08K 5/3432 20130101;
C08K 5/0091 20130101; C07D 207/00 20130101; B01J 20/22 20130101;
C07D 209/48 20130101; C08K 5/3417 20130101; B01J 20/06 20130101;
C08K 5/098 20130101; B65D 81/266 20130101; C08K 5/00 20130101; C08K
2201/012 20130101; C07D 209/46 20130101 |
International
Class: |
C07D 207/00 20060101
C07D207/00; C08K 5/00 20060101 C08K005/00; C07D 209/46 20060101
C07D209/46; C07D 209/48 20060101 C07D209/48; C07D 471/04 20060101
C07D471/04; C08K 5/098 20060101 C08K005/098; C08K 5/3417 20060101
C08K005/3417; B65D 81/26 20060101 B65D081/26; B01J 20/06 20060101
B01J020/06; B01J 20/22 20060101 B01J020/22; B01J 20/26 20060101
B01J020/26; B65D 65/38 20060101 B65D065/38; C08K 5/3432 20060101
C08K005/3432 |
Claims
1-78. (canceled)
79. A composition comprising organic material normally susceptible
to gradual degradation in the presence of oxygen during use over an
extended period containing an antioxidant effective amount of a
compound of the Formula I or II: ##STR00035## wherein X is selected
from the group consisting of O, S, and NH; wherein Y, A, and B are
independently selected from the group consisting of N and CH;
wherein D, E, and F are independently selected from the group
consisting of CH, N, O, and S; wherein the symbol ---- represents a
single or a double bond; and wherein R.sub.1, R.sub.2, and R.sub.3
are independently selected from the group consisting of H, electron
withdrawing groups, and electron releasing groups.
80. (canceled)
81. An oxygen scavenging composition that reacts with oxygen in the
presence of transition metals and salts thereof comprising an
effective amount of a compound of the Formula I or II: ##STR00036##
wherein X is selected from the group consisting of O, S, and NH;
wherein Y, A, and B are independently selected from the group
consisting of N and CH: wherein D, E, and F are independently
selected from the group consisting of CH, N, O, and S; wherein the
symbol ---- represents a single or a double bond; and wherein
R.sub.1, R.sub.2, and R.sub.3 are independently selected from the
group consisting of H, electron withdrawing groups, and electron
releasing groups.
82. An oxygen scavenging system comprising: (a) an oxygen
scavenging composition comprising a compound of the Formula I or
II: ##STR00037## wherein X is selected from the group consisting of
O, S, and NH; wherein Y, A, and B are independently selected from
the group consisting of N and CH; wherein D, E, and F are
independently selected from the group consisting of CH, N, O, and
S; wherein the symbol ---- represents a single or a double bond;
and wherein R.sub.1, R.sub.2, and R.sub.3 are independently
selected from the group consisting of H, electron withdrawing
groups, and electron releasing groups; (b) an effective amount of a
transition metal catalyst; and (c) a functional barrier permeable
to oxygen.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/928,553, filed May 10, 2007, the entirety of
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to compounds useful for oxygen
scavenging. The invention also relates to substantially transparent
compositions that comprise a base polymer, an oxidizable organic
component, and a transition metal. The invention also is directed
to uses of such compositions in the construction of packaging for
oxygen sensitive materials.
BACKGROUND OF THE INVENTION
[0003] It is known in the art to include an oxygen scavenger in the
packaging structure for the protection of oxygen sensitive
materials. Such scavengers are believed to react with oxygen that
is trapped in the package or that permeates from outside of the
package, thus extending to life of package contents. These packages
include films, bottles, containers, and the like. Food, beverages
(such as beer and fruit juices), cosmetics, medicines, and the like
are particularly sensitive to oxygen exposure and require high
barrier properties to oxygen to preserve the freshness of the
package contents and avoid changes in flavor, texture and
color.
[0004] Use of certain polyamides in combination with a transition
metal is known to be useful as the oxygen scavenging material. One
particularly useful polyamide is MXD6 which contains meta-xylene
residues in the polymer chain. See, for example, U.S. Pat. Nos.
5,639,815; 5,049,624; and 5,021,515.
[0005] Other oxygen scavengers include potassium sulfite (U.S. Pat.
No. 4,536,409), unsaturated hydrocarbons (U.S. Pat. No. 5,211,875),
and ascorbic acid derivatives (U.S. Pat. No. 5,075,362).
[0006] In barrier layers of packaging walls that are made from
blends of oxygen scavenging materials with base polymer resins such
as PET, haze can result due to such factors as the immiscibility of
the scavenging materials with the base polymer resins and the
inability to create by mechanical blending means disperse-phase
domains that are so small as not to interfere with the passage of
light therethrough; and the adverse influence of the scavenging
material on the crystallization behavior of PET base resin. One
approach to minimizing such haze is careful selection of base resin
to improve dispersibility of the scavenger material and, thus,
reduce, but not substantially eliminate, haze; and to minimize the
adverse crystallization effect. This approach may undesirably
narrowly restrict the choice of base polymer resin. Another
approach is to use compositions that serve as compatibilizers to
reduce haze. These approaches add cost to the layer and the
compatibilizer adds an additional material that must be evaluated
for its suitability for contact with food. Thus, there is a need in
the art for improved materials which provide high oxygen scavenging
capability and are substantially transparent.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to compositions
comprising:
[0008] (a) a base polymer;
[0009] (b) at least one compound of Formula 1 or 11
##STR00002##
[0010] wherein X is selected from the group consisting of O, S and
NH; Y, A and B are independently selected from the group consisting
of N and CH; D, E and F are independently selected from the group
consisting of CH, N, O and S; the symbol ---- when used in
conjunction with a bond line represents a single or a double bond;
and R.sub.1, R.sub.2 and R.sub.3 are independently selected from
the group consisting of H, electron withdrawing groups and electron
releasing groups and a transition metal; and (c) at least one
transition metal in a positive oxidation state, said metal being
present in the composition in an amount of 10 to 400 ppm; wherein
said compound is present in an amount of about 0.10 to 10 weight
percent of said composition. Methods of preparing, as well as
methods of implementing, the compositions of the present invention
are also described.
[0011] Also within the scope of the present invention are compounds
of Formulas I and II. Methods of preparing and using the compounds
of Formulas I and II are also described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows the percent oxygen in a vial containing MXBP, a
preferred embodiment of the present invention, over 18 days.
[0013] FIG. 2 shows that PET based plaques made with MXBP,
preferred embodiments of the present invention, scavenge
approximately 14% of oxygen in an enclosed environment after 25
days.
[0014] FIG. 3 Oxygen transmission data for Compound 306, a
preferred embodiment of the present invention. .box-solid.=QC
(reference sample comprising 1.5% MXD6, 2% cobalt masterbatch
(cobalt neodecanoate in PET); .tangle-solidup.=2'% Compound 306+2%
Cobalt Masterbatch+Vitiva; .diamond-solid.=air.
[0015] FIG. 4 Oxygen transmission data for Compound 310, a
preferred embodiment of the present invention. .box-solid.=QC
(reference sample comprising 1.5% MXD6, 2% cobalt masterbatch
(cobalt neodecanoate in PET); .tangle-solidup.=2.5% Compound 310+2%
Cobalt Masterbatch+Vitiva; .diamond-solid.=air.
[0016] FIG. 5 Oxygen transmission data for Compound 307, a
preferred embodiment of the present invention. .box-solid.=QC
(reference sample comprising 1.5% MXD6, 2% cobalt masterbatch
(cobalt neodecanoate in PET); .tangle-solidup.=4% Compound 307+2%
Cobalt Masterbatch+Vitiva; .diamond-solid.=air.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0017] In some embodiments, the invention concerns compounds of
Formula I and II:
##STR00003##
wherein X is selected from t e group consisting of O, S and NH; Y,
A and B are independently selected from the group consisting of N
and CH; D, E and F are independently selected from the group
consisting of CH, N, O and S; the symbol ----represents a single or
a double bond; and R.sub.1, R.sub.2 and R.sub.3 are independently
selected from the group consisting of H, electron withdrawing
groups and electron releasing groups.
[0018] In some aspects, the invention concerns compounds having the
formula:
##STR00004##
wherein X is O, S or NH; Y, A and B are independently N or CH; D, E
and F are independently CH, N, O or S; the symbol ---- in addition
to the solid line represents a single or a double bond; and
R.sub.1, R.sub.2 and R.sub.3 are independently H, electron
withdrawing groups or electron releasing groups.
[0019] In some compositions, X is O; Y, A and B are all CH; D, E,
and F are all CH; ---- is a double bond; and R.sub.1, R.sub.2 and
R.sub.3 are all hydrogen. Certain compositions have the formula
##STR00005##
[0020] Other compositions have the formula
##STR00006##
[0021] In other preferred embodiments, X is O; Y is N, A and B are
CH; D, E, and F are all CH; ---- is a double bond; and R.sub.1,
R.sub.2 and R.sub.3 are all hydrogen. Certain compositions of the
present invention have the formula:
##STR00007##
[0022] In yet other embodiments R.sub.1 and R.sub.3 are electron
releasing groups. Electron releasing groups, also known as electron
donating groups, are known in the art. Preferred electron releasing
groups include branched and straight chain alkyl groups, for
example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and
tert-butyl. Certain preferred compositions of the present invention
have the formula:
##STR00008##
[0023] Other preferred electron releasing groups include alkoxy,
for example methoxy and ethoxy. Still other preferred electron
releasing groups include amines, for example --NH.sub.2 and
N(loweralkyl).sub.2.
[0024] In still other embodiments, R.sub.1 and R.sub.3 are electron
withdrawing groups. Electron withdrawing groups are known in the
art. Preferred electron withdrawing groups include nitro,
carboxylic acid, esters, for example loweralkyl esters, and cyano.
Certain preferred compositions of the present invention have the
formula:
##STR00009##
[0025] Other preferred compositions of the present invention have
the formula:
##STR00010##
[0026] Yet other compositions of the present invention are of the
formula:
##STR00011##
wherein X is O, S or NH; Y, A and B are independently N or CH; D, E
and F are independently CH, N, O or S; the symbol ---- in addition
to the solid line represents a single or a double bond; and
R.sub.1, R.sub.2 and R.sub.3 are independently H, electron
withdrawing groups or electron releasing groups. In certain of
these compositions, X is O; Y, A and B are all CH; D, E, and F are
all CH; ---- is a double bond; and R.sub.1, R.sub.2 and R.sub.3 are
all hydrogen.
[0027] Other compositions of the invention have the formula
##STR00012##
[0028] In some aspects, the invention concerns organic material
normally susceptible to gradual degradation in the presence of
oxygen during use over an extended period containing an
antioxidant, or oxygen scavenging, effective amount of a compound
disclosed herein.
[0029] Some aspects of the invention concern containers comprising
a film-forming polymer, having at least one wall comprising an
effective amount of an oxygen-scavenging composition comprising a
compound disclosed herein.
[0030] Other aspects concern oxygen scavenging compositions that
react with oxygen in the presence of transition metals and salts
thereof comprising an effective amount of a compound disclosed
herein. The invention also relates to an oxygen scavenging system
comprising: (a) an oxygen scavenging composition comprising a
compound of Formula I or II; (b) an effective amount of a
transition metal catalyst; and (b) a functional barrier permeable
to oxygen.
[0031] The invention also relates to compositions comprising (a) a
base polymer; (b) at least one compound of Formula I or 11; and (c)
at least one transition metal in a positive oxidation state, the
metal being present in the composition in an amount of 10 to 400
ppm; where the compound is present in an amount of about 0.10 to 10
weight percent of the composition. One preferred transition metal
is cobalt. In some embodiments, the at least one transition metal
further comprises zinc. In other embodiments, the transition metal
comprises zinc and cobalt.
[0032] In some compositions, the base polymer comprises a polyester
polymer. One preferred polyester polymer is polyethylene
terephthalate.
[0033] The compound(s) described herein is present in an amount of
about 1 to about 10 weight percent based on the weight of the
composition in some embodiments. In other embodiments, the oxygen
scavenging compound is present in an amount of about 1 to about 5
weight percent based on the weight of the composition. In still
other embodiments, the compound is present in an amount of about 1
to about 3 weight percent based on the weight of the composition.
Also within the scope of the invention are those embodiments were
the compound(s) described herein is present in an amount of about
0.1 to about 10 weight percent based on the weight of the
composition.
[0034] Some preferred embodiments of the invention have a
concentration of transition metal from 30 to 150 ppm of the total
composition weight.
[0035] Other aspects of the invention concern package walls
comprising at least one layer, the layer comprising a composition,
the composition comprising: (a) a base polymer; (b) at least one
compound of Formula I or II; and (c) at least one transition metal
in a positive oxidation state, the metal being present in the
composition in an amount of 10 to 400 ppm; wherein the compound is
present in an amount of about 0.10 to 10 weight percent of the
composition.
[0036] Yet other aspects of the invention relate to package walls
comprising a composition, the composition comprising: (a) one or
more outer layers; and (b) one or more inner layers; wherein at
least one of the inner or at least one of the outer layers
comprises a composition comprising: (1) a base polymer; (2) at
least one compound of formula I or II; and (3) at least one
transition metal in a positive oxidation state, the metal being
present in the composition in an amount of 10 to 400 ppm; wherein
the compound is present in an amount of about 0.10 to 10 weight
percent of the composition. In some embodiments, the first layer is
disposed radially outward from the second layer.
[0037] The invention also relates to methods for packaging an
oxygen sensitive material comprising: [0038] (a) preparing a
package having a wall comprising at least one layer, at least one
of the layers comprising a composition, the composition comprising
[0039] a base polymer; [0040] at least one compound of Formula I or
11; and [0041] at least one transition metal in a positive
oxidation state, the metal being present in the composition in an
amount of 10 to 400 ppm; wherein the compound is present in an
amount of about 0.10 to 10 weight percent of the composition;
[0042] (b) introducing the oxygen sensitive material into the
package; and
[0043] (c) closing the package.
[0044] Still other embodiments of the invention concern methods for
producing a packaging material having a wall with oxygen barrier
properties comprising:
[0045] (a) combining a base polymer with at least one compound of
formula I or II to form a composition, the composition having at
least one transition metal in a positive oxidation state, the metal
being present in the composition in an amount of 10 to 400 ppm; and
wherein the compound is present in an amount of about 0.10 to 10
weight present of the composition;
[0046] (b) forming the product of step (a) into a wall; and
[0047] (c) forming a container which comprises the wall.
[0048] Another aspect of the invention concerns processes for
making an article comprising:
[0049] (a) forming a melt by combining in a melt processing zone:
[0050] a base polymer, [0051] at least one compound of formula I or
II, and [0052] at least one transition metal in a positive
oxidation state, the metal being present in the composition in an
amount of 10 to 400 ppm; wherein the compound is present in an
amount of about 0.10 to 10 weight present of the composition;
[0053] (b) forming an article from the melt.
[0054] In some embodiments, the article is a perform, a sheet, a
bottle, a cup, or a jar.
[0055] The terms "electron-withdrawing" or "electron-donating"
refer to the ability of a substituent to withdraw or donate
electrons relative to that of hydrogen if hydrogen occupied the
same position in the molecule. These terms are well-understood by
one skilled in the art and are discussed, for example, in Advanced
Organic Chemistry by J. March, 1985, pp. 16-18.
[0056] Electron withdrawing groups include fluoro, chloro, bromo,
nitro, acyl, cyano, carboxyl, lower alkenyl, lower alkynyl,
carboxaldehyde, carboxyamido, aryl, quaternary ammonium,
trifluoro-methyl, alkoxycarbonyl, aryloxycarbonyl, aminocarbonyl,
sulfonic, alkanesulfonyl, arylsulfonyl, perfluoroalkancsulfonyl,
perfluoroarylsulfonyl, phosphoryl, tertiary amine cation and a
combination thereof among others.
[0057] Electron donating groups include such groups as hydroxy,
lower alkoxy, lower alkyl, amino, lower alkylamino, di(lower
alkyl)amino, aryloxy, mercapto, lower alkylthio, lower
alkylmercapto and disulfide among others. One skilled in the art
will appreciate that the aforesaid substituents may have electron
donating or electron withdrawing properties under different
chemical conditions. Moreover, the present invention contemplates
any combination of substituents selected from the above-identified
groups.
[0058] In some embodiments, the most preferred electron donating or
electron withdrawing substituents are halo, nitro, alkanoyl,
carboxaldehyde, arylalkanoyl, aryloxy, carboxyl, carboxamide,
cyano, sulfonyl, sulfoxide, heterocyclyl, guanidine, quaternary
ammonium, lower alkenyl, lower alkynyl, sulfonium salts, hydroxy,
lower alkoxy, lower alkyl, amino, lower alkylamino, di(lower
alkylamino), amine lower mercapto, mercaptoalkyl, alkylthio and
alkyldithio.
[0059] The antioxidant/oxygen scavenger of the invention can be
used in a broad range of organic products normally subject to
gradual degradation in the presence of oxygen during use over an
extended period. In some embodiments, the organic compositions
protected by the present antioxidants are of the type in which the
art recognizes the need for antioxidant protection and to which an
antioxidant of some type is customarily added to obtain an extended
service life. The oxidative degradation protected against is the
slow gradual deterioration of the organic composition rather than,
for example, combustion. In other words, the present additives are
not necessarily flame retarding additives nor flame
suppressing.
[0060] In some embodiments, the antioxidant/oxygen scavenger can be
utilized at elevated temperatures. One such use would be during a
melt processing operation.
[0061] In some embodiments, the invention relates to synthesis of
the compounds of the invention. In a first synthetic scheme about 2
moles of a compound of the formula
##STR00013##
is reacted under reaction conditions to release water, which is
trapped in a Dean-Stark trap, with one mole of a compound of the
formula
##STR00014##
to produce the desired product having the formula:
##STR00015##
wherein all the groups are as defined above.
[0062] In one preferred embodiment, 2 moles of phthalide (also
known as o-hydroxymethyl-benzoic acid lactone or
1,3-dihydrobenzo[c]furan-1-one or oxophthalane or
1(3H)-isobenzo-furanone) are reacted with meta-xylylenediamine as
shown below:
##STR00016##
[0063] In another synthetic embodiment, phthalic anhydride is
reacted with metaxylylene diamine to produce the diimide product
and then as shown below:
##STR00017##
[0064] Further embodiments of the present invention can be prepared
using methods known generally in the art in accordance with the
following Schemes:
##STR00018##
##STR00019##
[0065] Even further embodiments can be prepared according to the
Schemes below:
##STR00020##
##STR00021##
[0066] Modifications known in the art can be used to produce
further embodiments of the present invention.
[0067] Examples of organic materials in which the additives are
useful include polymers, both homopolymers and copolymers, of
olefinically unsaturated monomers, for example, polyolefins such as
polyethylene, polypropylene, polybutadiene, and the like. Also,
poly-halohydrocarbons such as polyvinyl chloride, polychloroprene,
polyvinylidene chloride, polyfluoro olefins, and the like, are
afforded stabilization. The additives provide antioxidant
protection in natural and synthetic rubbers such as copolymers of
olefinically unsaturated monomers including styrene-butadiene
rubber (SBR rubber), ethylenepropylene copolymers,
ethylene-propylenediene terpolymers such as the terpolymer of
ethylene, propylene and cyclopentadiene or 1,4-cyclooctadiene.
Polybutadiene rubbers such as cis-polybutadiene rubber are
protected. Poly-2-chloro-1,3-butadiene (neoprene) and
poly-2-methyl-1,3-butadiene (isoprene rubber) are stabilized by the
present additives. Likewise, acrylonitrile-butadiene-styrene (ABS)
resins are effectively stabilized. Ethylenevinyl acetate copolymers
are protected, as are butene-methylacrylate copolymers.
Nitrogen-containing polymers such as polyurethanes, nitrite rubber,
and lauryl acrylate-vinyl-pyrrolidone copolymers are effectively
stabilized. Adhesive compositions such as solutions of
polychloroprene (neoprene) in toluene are protected.
[0068] Petroleum oils such as solvent-refined, midcontinent
lubricating oil and Gulfcoast lubricating oils are effectively
stabilized. In hydrocarbon lubricating oils, both mineral and
synthetic, the present additives are particularly effective when
used in combination with a zinc dihydrocarbyldithiophosphate, e.g.
zinc dialkyldithiophosphate or zinc dialkaryldithiophosphate.
[0069] Synthetic ester lubricants such as those used in turbines
and turbojet engines are given a high degree of stabilization.
Typical synthetic ester lubricants include di-2-ethylhexyl
sebacate, trimethylolpropane tripelargonate, C.sub.5-9 aliphatic
monocarboxylic esters of pentaerythritol, complex esters formed by
condensing under esterifying conditions, mixtures of polyols,
polycarboxylic acids, and aliphatic monocarboxylic acids and/or
monohydric alkanols. An example of these complex esters is the
condensation product formed from adipic acid, ethyleneglycol and a
mixture of C.sub.5-9 aliphatic monocarboxylic acids. Plasticizers
such as dioctyl phthalate are effectively protected. Heavy
petroleum fractions such as tar and asphalt can also be protected
should the need arise.
[0070] Polyamides such as adipic acid-1,6-diaminohexane condensates
and poly-6-aminohexanoic acid (nylon) are effectively stabilized.
Polyalkylene oxides such as copolymers of phenol with ethylene
oxide or propylene oxide are stabilized. Polyphenyl ethers such as
poly-2,6-dimethylphenyl ether formed by polymerization of
2,6-dimethylphenol using a copper-pyridine catalyst are stabilized.
Polycarbonate plastics and other polyformaldehydes are also
protected.
[0071] Linear polyesters such as phthalic anhydride-glycol
condensates are given a high degree of protection. Polyesters such
as those derived from terephthalic acid and alkylene glycols are
also given a high degree of protection. Other polyesters such as
trimellitic acid-glycerol condensates are also protected.
Polyacrylates such as polymethylacrylate and polymethylmethacrylate
are effectively stabilized. Polyacrylonitriles and copolymers of
acrylonitriles with other olefinically unsaturated monomers such as
methylmethacrylates are also effectively stabilized.
[0072] The additives can be used to protect any of the many organic
substrates to which an antioxidant is normally added. It can be
used where economics permit to protect such substrates as asphalt,
paper, fluorocarbons such as Teflon.RTM., polyvinyl acetate,
polyvinylidene chloride, coumarone-indene resins, polyvinyl ethers,
polyvinylidene bromide, polyvinyl bromide, acrylonitrile, vinyl
bromide copolymer, vinyl butyral resins, silicones such as
dimethylsilicone lubricants, phosphate lubricants such as
tricresylphosphate, and the like.
[0073] A preferred embodiment of the invention is the incorporation
of the oxygen scavenger into polyethylene terephthalate
formulations which further include a transition metal catalyst. The
oxygen scavenger works particularly well in the presence of the
transition metal catalyst.
[0074] In combination with the polymer components, the oxygen
scavenging compositions including compounds of formula I or II of
the present invention may include a transition metal salt, compound
or complex, as an oxygen scavenger catalyst. The transition metal
can be selected from the first, second, or third transition series
of the Periodic Table. The metal can be Rh, Ru, or one of the
elements in the series of Sc to Zn (i.e., Sc, Ti, V, Cr, Mn, Fe,
Co, Ni, Cu, and Zn). Suitable anions for the salts include, but are
not limited to, chloride, acetate, oleate, stearate, palmitate,
2-ethylhexanoate, neodecanoate, and naphthenate. Representative
salts include cobalt (II) 2-ethylhexanoate, cobalt oleate, and
cobalt (11) neodecanoate. The metal salt also can be an ionomer, in
which case a polymeric counter ion may be employed.
[0075] The amounts of the components used in the oxygen scavenging
formulations of the present invention can affect the use and
effectiveness of this composition. Thus, the amounts of polymer,
transition metal catalyst, antioxidant, polymeric diluents,
additives, etc., can vary depending on the desired article and its
end use. For example, one of the primary functions of the polymers
described above is to react irreversibly with oxygen during the
scavenging process, while a primary function of the transition
metal catalyst is to facilitate this process. Thus, to a large
extent, the amount of polymer present affects the oxygen scavenging
capacity of the composition, i.e., the amount of oxygen that the
composition can consume, while the amount of transition metal
catalyst affects the rate at which oxygen is consumed as well as
the induction period.
[0076] Methods of incorporating the additive into the substrate are
well known. For example, if the substrate is liquid the additive
can be merely mixed into the substrate. Frequently the organic
substrate is in solution and the additive is added to the solution
and the solvent removed. Solid organic substrates can be merely
sprayed with a solution of the additive in a volatile solvent. For
example, stabilized grain products result from spraying the grain
with a toluene solution of the additive. In the case of rubbery
polymers the additive can be added following the polymerization
stage by mixing it with the final emulsion or solution
polymerization mixture and then coagulating or removing solvent to
recover the stabilized polymer. It can also be added at the
compounding stage by merely mixing the additive with the rubbery
polymer in commercial mixing equipment such as a Banbury blender.
In this manner, rubbery polymers such as styrene-butadiene rubber,
cispolybutadiene or isoprene polymers are blended with the
antioxidant together with the other ingredients normally added such
as carbon black, oil, sulfur, zinc oxide, stearic acid,
vulcanization accelerators, and the like. Following mastication,
the resultant mixture is fabricated and molded into a finished form
and vulcanized.
[0077] The oxygen scavenger composition of the present invention
can be incorporated in packaging articles having various forms.
Suitable articles include, but are not limited to, flexible sheet
films, flexible bags, pouches, semi-rigid and rigid containers such
as bottles (e.g. PET bottles) or metal cans, or combinations
thereof.
[0078] Typical flexible films and bags include those used to
package various food items and may be made up of one or a
multiplicity of layers to form the overall film or bag-like
packaging material. The oxygen scavenger composition of the present
invention can be used in one, some or all of the layers of such
packaging material.
[0079] Typical rigid or semi-rigid articles include plastic, paper
or cardboard containers, such as those utilized for juices, soft
drinks, as well as thermoformed trays or cup normally having
thickness in the range of from 100 to 1000 micrometers. The walls
of such articles can comprise single or multiple layers of
materials. The articles can also take the form of a bottle or metal
can, or a crown, cap, crown or cap liner, plastisol or gasket. The
oxygen scavenger composition of the present invention can be used
as an integral layer or portion of, or as an external or internal
coating or liner of, the formed semi-rigid or rigid packaging
article. As a liner, the oxygen scavenger composition can be
extruded as a film along with the rigid article itself, in e.g. a
coextrusion, extrusion coating, or extrusion lamination process, so
as to form the liner in situ during article production; or
alternatively can be adhered by heat and/or pressure, by adhesive,
or by any other suitable method to an outer surface of the article
after the article has been produced.
[0080] Although it may be preferable from the standpoint of
packaging convenience and/or scavenging effectiveness to employ the
present invention as an integral or discrete part of the packaging
wall, the invention can also be used as a non-integral component of
a packaging article such as, for example, a bottle cap liner,
adhesive or non-adhesive sheet insert, sealant, sachet, fibrous mat
insert or the like.
[0081] Besides articles applicable for packaging food and beverage,
articles for packaging other oxygen-sensitive products can also
benefit from the present invention. Such products would include
pharmaceuticals, oxygen sensitive medical products, corrodible
metals or products, electronic devices and the like.
[0082] In some embodiments of the invention, the base polymer in
the composition is a polyester. In certain embodiments, the
polyester polymers of the invention are thermoplastic and, thus,
the form of the compositions are not limited and can include a
composition in the melt phase polymerization, as an amorphous
pellet, as a solid stated polymer, as a semi-crystalline particle,
as a composition of matter in a melt processing zone, as a bottle
preform, or in the form of a stretch blow molded bottle or other
articles. In certain preferred embodiments, the polyester is
polyethylene terephthalate (PET).
[0083] Examples of suitable polyester polymers include polyethylene
terephthalate homopolymers and copolymers modified with one or more
polycarboxylic acid modifiers in a cumulative amount of less than
about 15 mole %, or about 10 mole % or less, or about 8 mole % or
less, or one or more hydroxyl compound modifiers in an amount of
less than about 60 mol %, or less than about 50 mole %, or less
than about 40 mole %, or less than about 15 mole %, or about 10
mole % or less, or about 8 mole % or less (collectively referred to
for brevity as "PET") and polyethylene naphthalate homopolymers and
copolymers modified with a cumulative amount of with less than
about 15 mole %, or about 10 mole % or less, or about 8 mole % or
less, of one or more polycarboxylic acid modifiers or modified less
than about 60 mol %, or less than about 50 mole %, or less than
about 40 mole %, or less than about 15 mole %, or about 10 mole %
or less, or about 8 mole % or less of one or more hydroxyl compound
modifiers (collectively referred to herein as "PEN"), and blends of
PET and PEN. A modifier polycarboxylic acid compound or hydroxyl
compound is a compound other than the compound contained in an
amount of at least about 85 mole %. The preferred polyester polymer
is polyalkylene terephthalate, and most preferred is PET.
[0084] In some embodiments, the polyester polymer contains at least
about 90 mole % ethylene terephthalate repeat units, and in other
embodiments, at least about 92 mole %, and in yet other
embodiments, or at least about 94 mole %, based on the moles of all
repeat units in the polyester polymers.
[0085] In addition to a diacid component of terephthalic acid,
derivates of terephthalic acid, naphthalene-2,6-dicarboxylic acid,
derivatives of naphthalene-2,6-dicarboxylic acid, or mixtures
thereof, the polycarboxylic acid component(s) of the present
polyester may include one or more additional modifier
polycarboxylic acids. Such additional modifier polycarboxylic acids
include aromatic dicarboxylic acids preferably having about 8 to
about 14 carbon atoms, aliphatic dicarboxylic acids preferably
having about 4 to about 12 carbon atoms, or cycloaliphatic
dicarboxylic acids preferably having about 8 to about 12 carbon
atoms. Examples of modifier dicarboxylic acids useful as an acid
component(s) are phthalic acid, isophthalic acid,
naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,
cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic
acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and
the like, with isophthalic acid, naphthalene-2,6-dicarboxylic acid,
and cyclohexanedicarboxylic acid being most preferable. It should
be understood that use of the corresponding acid anhydrides,
esters, and acid chlorides of these acids is included in the term
"polycarboxylic acid." It is also possible for trifunctional and
higher order polycarboxylic acids to modify the polyester.
[0086] The hydroxyl component is made from compounds containing 2
or more hydroxyl groups capable of reacting with a carboxylic acid
group. In some preferred embodiments, preferred hydroxyl compounds
contain 2 or 3 hydroxyl groups. Certain preferred embodiments, have
2 hydroxyl groups. These hydroxyl compounds include C.sub.2-C.sub.4
alkane diols, such as ethylene glycol, propane diol, and butane
diol, among which ethylene glycol is most preferred for container
applications. In addition to these diols, other modifier hydroxyl
compound component(s) may include diols such as cycloaliphatic
diols preferably having 6 to 20 carbon atoms and/or aliphatic diols
preferably having about 3 to about 20 carbon atoms. Examples of
such diols include diethylene glycol; triethylene glycol;
1,4-cyclohexanedimethanol; propane-1,3-diol and butane-1,4-diol
(which are considered modifier diols if ethylene glycol residues
are present in the polymer in an amount of at least 85 mole % based
on the moles of all hydroxyl compound residues); pentane-1,5-diol;
hexane-1,6-diol; 3-methylpentanediol-(2,4); neopentyl glycol;
2-methylpentanediol-(1,4); 2,2,4-trimethylpentane-diol-(1,3);
2,5-ethylhexanediol-(1,3); 2,2-diethyl propane-diol-(1, 3);
hexanediol-(1,3); 1,4-di-(hydroxyethoxy)-benzene;
2,2-bis-(4-hydroxycyclohexyl)-propane;
2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane;
2,2-bis-(3-hydroxyethoxyphenyl)-propane; and
2,2-bis-(4-hydroxypropoxyphenyl)-propane. Typically, polyesters
such as polyethylene terephthalate are made by reacting a glycol
with a dicarboxylic acid as the free acid or its dimethyl ester to
produce an ester monomer and/or oligomers, which are then
polycondensed to produce the polyester.
[0087] In some preferred embodiments, modifiers include isophthalic
acid, naphthalenic dicarboxylic acid, trimellitic anhydride,
pyromellitic dianhydride, 1,4-cyclohexane dimethanol, and
diethylene glycol. The amount of the polyester polymer in the
formulated polyester polymer composition ranges from greater than
about 50.0 wt. %, or from about 80.0 wt. %, or from about 90.0 wt.
%, or from about 95.0 wt. %, or from about 96.0 wt. %, or from
about 97 wt. %, and up to about 99.90 wt. %, based on the combined
weight of all polyester polymers and all polyamide polymers. The
formulated polyester polymer compositions may also include blends
of formulated polyester polymer compositions with other
thermoplastic polymers such as polycarbonate. In some preferred
compositions, the polyester comprises a majority of the composition
of the inventions, and in some embodiments the polyester is present
in an amount of at least about 80 wt. %, or at least about 90 wt.
%, based on the weight of the composition (excluding fillers,
inorganic compounds or particles, fibers, impact modifiers, or
other polymers serve as impact modifiers or which form a
discontinuous phase such as may be found in cold storage food
trays).
[0088] The polyester compositions can be prepared by polymerization
procedures known in the art sufficient to effect esterification and
polycondensation. Polyester melt phase manufacturing processes
include direct condensation of a dicarboxylic acid with the diol,
optionally in the presence of esterification catalysts, in the
esterification zone, followed by polycondensation in the prepolymer
and finishing zones in the presence of a polycondensation catalyst;
or ester exchange usually in the presence of a transesterification
catalyst in the ester exchange zone, followed by prepolymerization
and finishing in the presence of a polycondensation catalyst, and
each may optionally be solid stated according to known methods.
[0089] The transition metal used in the instant compositions is a
metal in the positive oxidation state. It should be noted that it
is contemplated that one or more such metals may be used. In some
embodiments, cobalt is added in +2 or +3 oxidation state. In some
embodiments, it is preferred to use cobalt in the +2 oxidation
state. In certain embodiments, copper in the +2 oxidation state is
utilized. In some embodiments, rhodium in the +2 oxidation state is
used. In certain embodiments, zinc may also be added to the
composition. Preferred zinc compounds include those in a positive
oxidation state.
[0090] Suitable counter-ions to the transition metal cations
include carboxylates, such as neodecanoates, octanoates, acetates,
lactates, naphthalates, malates, stearates, acetylacetonates,
linolcates, olcates, palmitates, 2-ethylhexanoates, or ethylene
glycolates; or as their oxides, borates, carbonates, chlorides,
dioxides, hydroxides, nitrates, phosphates, sulfates, or silicates
among others.
[0091] In some embodiments, levels of at least about 10 ppm, or at
least about 50 ppm, or at least about 100 ppm of metal can achieve
suitable oxygen scavenging levels. The exact amount of transition
metal used in an application can be determined by trials that are
well within the skill level of one skilled in the art. In some
embodiments involving wall applications (as opposed to master batch
applications where more catalyst is used), it is preferred to keep
the level of metal below about 300 ppm and, in other embodiments,
preferably below about 250 ppm.
[0092] The transition metal or metals may be added neat or in a
carrier (such as a liquid or wax) to an extruder or other device
for making the article, or the metal may be present in a
concentrate or carrier with the oxidizable organic component, in a
concentrate or carrier with a base polymer, or in a concentrate or
carrier with a base polymer/oxidizable organic component blend.
Alternatively, at least a portion of the transition metal may be
added as a polymerization catalyst to the melt phase reaction for
making the base polymer (a polyester polymer in some embodiments)
and be present as residual metals when the polymer is fed to the
melting zone (e.g. the extrusion or injection molding zone) for
making the article such as a preform or sheet. It is desirable that
the addition of the transition metal does not substantially
increase the intrinsic viscosity (It.V) of the melt in the melt
processing zone. Thus, transition metal or metals may be added in
two or more stages, such as once during the melt phase for the
production of the polyester polymer and again once more to the
melting zone for making the article.
[0093] The composition may also include other components such as
pigments, fillers, crystallization aids, impact modifiers, surface
lubricants, denesting agents, stabilizers, ultraviolet light
absorbing agents, metal deactivators, nucleating agents such as
polyethylene and polypropylene, phosphate stabilizers and
dyestuffs. Other additional components are well known to those
skilled in the art and can be added to the existing composition so
long as they do not negatively impact the performance of the
compositions. Typically, the total quantity of such components will
be less than about 10% by weight relative to the whole composition.
In some embodiments, the amount of these optional components is
less than about 5%, by weight relative to the total
composition.
[0094] A common additive used in the manufacture of polyester
polymer compositions used to make stretch blow molded bottles is a
reheat additive because the preforms made from the composition must
be reheated prior to entering the mold for stretch blowing into a
bottle. Any of the conventional reheat additives can be used, such
additives include various forms of black particles, e.g. carbon
black, activated carbon, black iron oxide, glassy carbon, and
silicon carbide; the gray particles such as antimony, and other
reheat additives such as silicas, red iron oxide, and so forth.
[0095] Other typical additives, depending on the application, are
impact modifiers. Examples of typical commercially available impact
modifiers well-known in the art and useful in this invention
include ethylene/acrylate/glycidyl terpolymers and
ethylene/acrylate copolymers in which the acrylate is a methyl or
ethyl acrylate or methyl or ethyl methacrylate or the corresponding
butyl acrylates, styrene based block copolymers, and various
acrylic core/shell type impact modifiers. The impact modifiers may
be used in conventional amounts from about 0.1 to about 25 weight
percent of the overall composition and, in some embodiments,
preferably in amounts from about 0.1 to about 10 weight percent of
the composition.
[0096] In many applications, not only are the packaging contents
sensitive to the ingress of oxygen, but the contents may also be
affected by UV light. Fruit juices and pharmaceuticals are two
examples of such contents. Accordingly, in some embodiments, it is
desirable to incorporate into the polyester composition any one of
the known UV absorbing compounds in amounts effective to protect
the packaged contents.
[0097] The instant compositions can be made by mixing a base
polymer (PET, for example) with the oxidizable organic component
and the transition metal composition. Such compositions can be made
by any method known to those skilled in the art. In certain
embodiments, some or part of the transition metal may exist in the
base polymer prior to mixing. This residual metal, for example, can
exist from the manufacturing process of the base polymer. In some
embodiments, the base polymer, the oxidizable organic component and
the transition metal are mixed by tumbling in a hopper. Other
optional ingredients can be added during this mixing process or
added to the mixture after the aforementioned mixing or to an
individual component prior to the aforementioned mixing step.
[0098] The instant composition can also be made by adding each
ingredient separately and mixing the ingredients prior melt
processing the composition to form an article. In some embodiments,
the mixing can be just prior to the melt process zone. In other
embodiments, one or more ingredients can be premixed in a separate
step prior to bringing all of the ingredients together.
[0099] In some embodiments, the invention concerns use of the
compositions described herein as a component of a wall that is used
in a package for oxygen sensitive materials. The necessary
scavenging capacity of a package will generally have to be greater
for walls that have a greater permeance in the absence of
scavenging additives. Accordingly, a good effect is harder to
achieve with inherently higher permeance materials are used.
[0100] The wall may be a rigid one, a flexible sheet, or a clinging
film. It may be homogenous or a laminate or coated with other
polymers. If it is laminated or coated, then the scavenging
property may reside in a layer of the wall the permeance of which
is relatively high in the absence of scavenging and which alone
would not perform very satisfactorily but which performs
satisfactorily in combination with one or more other layers which
have a relatively low permeance but negligible or insufficient
oxygen-scavenging properties. A single such layer could be used on
the outside of the package since this is the side from which oxygen
primarily comes when the package is filled and sealed. However,
such a layer to either side of the scavenging layer would reduce
consumption of scavenging capacity prior to filling and
scaling.
[0101] When the instant compositions are used in a wall or as a
layer of a wall, the permeability of the composition for oxygen is
advantageously not more than about 3.0, or about 1.7, or about 0.7,
or about 0.2, or about 0.03 cm.sup.3 mm/(m.sup.2 atm day). The
permeability of the composition provided by the present invention
is advantageously not more than about three-quarters of that in the
absence of oxygen-scavenging properties. In some embodiments, the
permeability is not more than about one half, one-tenth in certain
embodiments, one twenty-fifth in other embodiments, and not more
than one-hundredth in yet other embodiments of that in the absence
of oxygen-scavenging properties. The permeability in the absence of
oxygen-scavenging properties is advantageously not more than about
17 cm.sup.3 mm/(m.sup.2 atm day), or about 10, and or about 6. A
particularly good effect can be achieved for such permeabilities in
the range from about 0.5, or about 1.0, to 10, or about 6.0,
cm.sup.3 mm/(m.sup.2 atm day). Measurements of oxygen permeation
can be made by methods described, for example, in U.S. Pat. No.
5,639,815, the contents of which are incorporated herein in its
entirety.
[0102] In another aspect, the instant composition can be used as a
master batch for blending with a polymer or a polymer containing
component. In such compositions, the concentration of the
oxidizable organic component and the transition metal will be
higher to allow for the final blended product to have suitable
amounts of these components. The master batch may also contain an
amount of the polymer to which the master batch is to be blended
with. In other embodiments, the master batch may contain a polymer
that is compatible with the polymer that the master batch is to be
blended with.
[0103] In yet another aspect, the compositions of the instant
invention can be used for forming a layer of a wall which primarily
provides oxygen-scavenging (another layer including polymer
providing gas barrier without significant scavenging), or as a
head-space scavenger (completely enclosed, together with the
package contents, by a package wall). Such techniques are well know
to those skilled in the art. Persons familiar with oxygen
scavenging technology and products will understand how to implement
the structures disclosed in this paragraph.
[0104] The time period for which the permeability is maintained can
be extended by storing the articles in scaled containers or under
an inert atmosphere such as nitrogen prior to use with oxygen
sensitive materials.
[0105] In another aspect, the invention provides a package, whether
rigid, semi-rigid, collapsible, lidded, or flexible or a
combination of these, comprising a wall as formed from the
compositions described herein. Such packages can be formed by
methods well known to those skilled in the art.
[0106] Among the techniques that may be used to make articles are
moulding generally, injection moulding, stretch blow moulding,
extrusion, thermoforming, extrusion blow moulding, and
(specifically for multilayer structures) co-extrusion and
lamination using adhesive tie layers. Orientation, e.g. by stretch
blow moulding, of the polymer is especially attractive with
phthalate polyesters because of the known mechanical advantages
that result.
[0107] The melt processing zone for making the article can be
operated under customary conditions effective for making the
intended articles, such as preforms, bottles, trays, and other
articles mentioned below. In one embodiment, such conditions are
effective to process the melt without substantially increasing the
It.V. of the melt and which are ineffective to promote
transesterification reactions. In some preferred embodiments,
suitable operating conditions effective to establish a physical
blend of the polyester polymer, oxidizable organic component, and
transition metal are temperatures in the melt processing zone
within a range of about 250.degree. C. to about 300.degree. C. at a
total cycle time of less than about 6 minutes, and typically
without the application of vacuum and under a positive pressure
ranging from about 0 psig to about 900 psig. In some embodiments,
the residence time of the melt on the screw can range from about 1
to about 4 minutes.
[0108] Specific articles include preforms, containers and films for
packaging of food, beverages, cosmetics, pharmaceuticals, and
personal care products where a high oxygen barrier is needed.
Examples of beverage containers are bottles for holding water and
carbonated soft drinks, and the invention is particularly useful in
bottle applications containing juices, sport drinks, beer or any
other beverage where oxygen detrimentally affects the flavor,
fragrance, performance (prevent vitamin degradation), or color of
the drink. The compositions of the instant invention are also
particularly useful as a sheet for thermoforming into rigid
packages and films for flexible structures. Rigid packages include
food trays and lids. Examples of food tray applications include
dual ovenable food trays, or cold storage food trays, both in the
base container and in the lidding (whether a thermoformed lid or a
film), where the freshness of the food contents can decay with the
ingress of oxygen. The compositions of the instant invention also
find use in the manufacture of cosmetic containers and containers
for pharmaceuticals or medical devices.
[0109] The package walls of the instant invention can be a single
layer or a multilayer constructions. In some embodiments using
multilayer walls, the outer and inner layers may be structural
layers with one or more protective layers containing the oxygen
scavenging material positioned there between. In some embodiments,
the outer and inner layers comprise and polyolefin or a polyester.
In certain embodiments, a single layer design is preferred. Such a
layer may have advantages in simplicity of manufacture and
cost.
[0110] Unless otherwise indicated, the invention is not limited to
specific molecular structures, substituents, synthetic methods,
reaction conditions, or the like, as such may vary. It is also to
be understood that the terminology used herein is for the purpose
of describing particular embodiments only and is not intended to be
limiting.
[0111] In this specification and in the claims that follow,
reference will be made to a number of terms, which shall be defined
to have the following meanings:
[0112] As used herein, the phrase "having the formula" or "having
the structure" is not intended to be limiting and is used in the
same way that the term "comprising" is commonly used. The term
"independently selected from" is used herein to indicate that the
recited elements, e.g., R groups or the like, can be identical or
different.
[0113] As used herein, the terms "a", "an", "the" and the like
refer to both the singular and plural unless the context clearly
indicates otherwise. "A bottle", for example, refers to a single
bottle or more than one bottle.
[0114] Also as used herein, the description of one or more method
steps does not preclude the presence of additional method steps
before or after the combined recited steps. Additional steps may
also be intervening steps to those described. In addition, it is
understood that the lettering of process steps or ingredients is a
convenient means for identifying discrete activities or ingredients
and the recited lettering can be arranged in any sequence.
[0115] Where a range of numbers is presented in the application, it
is understood that the range includes all integers and fractions
thereof between the stated range limits. A range of numbers
expressly includes numbers less than the stated endpoints and those
in-between the stated range. A range of from 1-3, for example,
includes the integers one, two, and three as well as any fractions
that reside between these integers.
[0116] As used herein, "master batch" refers to a mixture of base
polymer, oxidizable organic component, and transition metal that
will be diluted, typically with at least additional base polymer,
prior to forming an article. As such, the concentrations of
oxidizable organic component and transition metal are higher than
in the formed article.
[0117] The following examples are included to demonstrate preferred
embodiments of the invention regarding synthesis of the molecules
and use of the molecules to scavenge oxygen as well products
containing such scavengers. It should be appreciated by those of
skill in the art that the techniques disclosed in the examples
which follow represent techniques discovered by the inventors to
function well in the practice of the invention, and thus can be
considered to constitute preferred modes for its practice. However,
those of skill in the art should, in light of the present
disclosure, appreciate that many changes can be made in the
specific embodiments which are disclosed and still obtain a like or
similar result without departing from the spirit and scope of the
invention.
EXAMPLES
Example 1
[0118] 2 g of MXBP is placed in a 22 cc vial having an oxygen
sensitive oxydot on the sidewall of the vial. The vial is sealed
such that there is no exchange with the outside environment. A
scaled, empty air vial was used as control.
##STR00022##
[0119] Initial percent oxygen levels in the vials are measured at
room temperature (.about.22.degree. C.) using an Oxysense
instrument (Oxysense, Inc., Las Vegas, Nev.). The vials are then
placed in an air-circulated oven at 75.degree. C. After 1 day in
the oven, the vials are removed, cooled to room temperature, and
measured for percent oxygen levels. After measurement of 5 oxygen
levels, the vials are returned to the 75.degree. C. oven. This
procedure is repeated for 18 days. Data generated from these
measurements is shown in FIG. 1.
[0120] As seen in FIG. 1, MXBP scavenges approximately 4% of oxygen
after 18 days.
Example 2
[0121] PET resin (Vitiva.TM., Eastman Chemical Company, Kingsport,
Tenn.) is dried in a Piovan Dryer (Model # DSN 520 HE, Piovan
Canada, Mississauga, Ontario), at 170.degree. C. for 4 hours (dew
point of air used=-50.degree. C.) prior to being fed to an
injection molding machine. Moisture content of the resin (after 4
hrs/170.degree. C.) is measured by a Mark 2 HP Moisture analyzer
(Sartorious Omnimark Instrument Corp., Temp, Ariz.). The moisture
content of the dried PET is approximately 33 ppm.
[0122] Cobalt containing polyester (Masterbatch) (4000 ppm Cobalt)
is dried in a Dri Air Model RH 15 dryer (Dri-Air Industries, Inc.,
East Windsor, Conn.) at 291.degree. F. for 3 hours.
[0123] A mixture of 2.5 wt % MXBP powder, 2 wt % Cobalt
Masterbatch, and 95.5 wt % Vitiva is blended in a bucket. The
mixture is poured in the feed hopper of a Husky LX160 injection
molding machine (two-cavity, 160 tonnes clamping pressure, Husky
Injection Molding Systems Ltd., Novi, Mich.) to produce preforms.
The preforms made from this mixture are for a 16 oz. stock hot fill
(36 gram preform weight) bottle. The preforms are blown into a
bottle on a Sidel SBO 2/3 blow molding machine (Sidel Inc.,
Norcross, Ga.).
[0124] A portion of the Monomer MXBP bottle sidewall was analyzed
for cobalt and nitrogen content at Gas Technology Institute, Des
Plaines, Ill. Cobalt levels are determined to be approximately 67
ppm and the nitrogen content is approximately 0.11 ppm. This
corresponds to approximately 1.45 weight percent of MXBP in the
bottle wall.
Example 3--Preparation of QC (Reference)
[0125] A preform containing nylon MXD6 (1.5%, based on total weight
of preform), cobalt masterbatch (2%, based of total weight of
preform), in PET is prepared. The preform is then ground up and
used as a control during oxygen scavenging testing.
Example 4
[0126] Approximately two weeks after being blown, six bottles
prepared according to Example 2 are placed on an Illiop oxygen
transmission measuring machine (Constar International, Inc.,
Philadelphia, Pa.) to measure oxygen transmission rate. The steady
state oxygen permeation rate for all the bottles was found to be
approximately 0.0005 cc/pkg/day (see Table 1).
TABLE-US-00001 TABLE 1 Bottle No. 15 17 18 19 20 21 Equilibrium
0.0005 0.0007 0.0004 0.0004 0.0004 0.0005 Transmission Rate
(mL/pkg/day)
Example 5
[0127] PET resin (Vitiva.TM., Eastman Chemical Company, Kingsport,
Tenn.) is dried in a Nissei dryer at 170.degree. C. for 4 hours
prior to use. Cobalt containing polyester (Masterbatch) (4000 ppm
Cobalt) is dried for approximately 2 hours at 350.degree. F. prior
to use.
[0128] Plaques (approximately 33.5 gram weight) are molded on
30-ton BOY 22S injection molding machine using the following
settings:
TABLE-US-00002 Barrel temperature 264.degree. C. Nozzle heater
setting 35% of the power used to heat the barrel Sprue heater set
temperature approx. 215.degree. C. Injection pressure mold 600 psi
(20 sec. of hold pressure; 15 sec. cooling time) The mold is water
cooled with process water flow rate at approximately 0.5 LPM.
[0129] MXBP powder (25.09 g) is hand blended in a bucket with dried
Masterbatch (20.09 g) and dried PET (958.4 g). This mixture is
poured in the feed hopper of the BOY 22S machine.
[0130] The first 10 plaques are discarded as change-over plaques.
After the first 10 plaques are discarded, 8 plaques are collected
for oxygen scavenging evaluation. Data generated from oxygen
scavenging evaluation is shown in FIG. 2.
[0131] As seen in FIG. 2, PET plaques containing MXBP scavenge
approximately 14% of oxygen after 25 days.
Example 6 Preparation of MXBP
##STR00023##
[0133] To phthalide 674.1 g. (5.026 mol) heated to 115.degree. C.
was added m-xylylenediamine 325.9 g (2.393 mol) with nitrogen
sparge. The solution was heated to 190.degree. C. and held for 1.5
hours during which time 20 mL of water distillate was collected in
a Dean-Stark trap. The heat was then increased to 200.degree. C.
and held for 3.5 hours during which time an additional 23 mL of
water was collected. The heat was then was increased to 210.degree.
C. and held for 12 hours during which time an additional 15 mL of
water was collected. The amine value by titration with 0.1 N
perchloric acid in glacial acetic acid was 28.1 mg KOH/gram of
sample. Reaction was held an additional 7 hours at 215.degree. C.
during which time an additional 2 mL of water was collected and the
amine value had dropped to 18.1 mg KOH/gram of sample. This
solution was cooled to 125.degree. C. and 1-methyl-2-pyrrolidinone
500 grams was added. The solution was cooled to 90.degree. C. and
poured into water 4 L containing glacial acetic acid 40 g with
mixing to create a slurry. This was filtered to yield 1000 g of
press cake. This was added to isopropanol (IPA) 1000 g and water
2000 g and the resulting slurry was filtered to yield 1000 g of
press cake. This was added to IPA 2200 g and the resulting slurry
was filtered to yield 1600 g of press cake. This was added to IPA
1500 g and the resulting slurry was filtered to yield 1350 g of
press cake. This was added to IPA 1300 g and the resulting slurry
was filtered to yield 1240 g of press cake. This was dried at
60.degree. C. to yield 671 g (73.4% yield) of product. Its melting
point was 154-157.degree. C. The amine value was less than 0.5 mg
KOH/gram of sample. The infrared spectra was consistent with the
desired product.
Example 7 Alternative Preparation of MXBP
##STR00024##
[0135] To phthalide 505.6 g (3.769 mol) heated to 115.degree. C.
was added m-xylylenediamine 244.4 g (1.795 mol) with nitrogen
sparge. The solution was heated to 180.degree. C. and held for 3.5
hours during which time 14 mL of water distillate was collected in
a Dean-Stark trap. The heat was then increased to 190.degree. C.
and held for 20 hours during which time an additional 15 mL of
water was collected. The amine value was 47 mg KOH/gram of sample.
The heat was then increased to 205.degree. C. and held for 7 hours
during which time an additional 22 mL of water was collected. The
amine value was 30 mg KOH/gram of sample. The heat was then
increased to 210.degree. C. and held for 15 hours during which time
an additional 5 mL of water was collected. The amine value was 11.7
mg KOH/gram of sample. The solution was cooled to 185.degree. C.
and cast into an aluminum tray to yield 661.7 g of a clear, amber
solid. This was purified as shown in the following examples.
Example 8--Purification Methods for MXBP
Method A
[0136] To IPA 450 g and I-methyl-2-pyrrolidinone 180 g was added
the product of Example 6 330 g and the mixture was heated to
90.degree. C. to produce a clear solution. This was poured into
water 2000 mL and IPA 500 g to create a slurry. This was filtered
and washed with IPA 300 g to yield 495 g of press cake. This was
added to IPA 2500 g and filtered to yield 495 g press cake. This
was added to IPA 1500 g and filtered to yield 455 g of press cake.
This was dried at 60.degree. C. to yield 219 g (66.4% yield) of the
desired product.
Method B
[0137] To xylene 247 g was added the product of Example 6 165 g and
the mixture was heated to 140.degree. C. to produce a clear
solution. The solution was cooled to 50.degree. C. and xylene 100 g
was added. The resulting slurry was cooled to 30.degree. C. This
was filtered and washed with xylene 200 g to yield 203 g of press
cake. This was added to IPA 800 g and heated to 80.degree. C. to
produce a clear solution. The solution was cooled to 36.degree. C.
and IPA 200 g was added. The resulting slurry was cooled to
30.degree. C. and held 0.5 hours. This was filtered and washed with
IPA 200 g to yield 232 g of press cake. This was air dried at
ambient temperature to yield 110 g (66.7% yield) of the desired
product.
Method C
[0138] To IPA 700 g was added the product of Example 6 140 g and
the mixture was heated to 80' C to produce a clear solution. The
solution was cooled to 32.degree. C. and IPA 200 g was added. The
resulting slurry was cooled to 30.degree. C. and held 0.5 hours.
This was filtered and washed with IPA 200 g to yield 220 g press
cake. This was added to IPA 600 g and heated to 80.degree. C. to
produce a clear solution. This was cooled to 39.degree. C. and IPA
200 g was added. The resulting slurry was cooled to 30.degree. C.
and held 0.5 hours. This was filtered and washed with IPA 200 g to
yield 232 g of press cake. This was air dried at ambient
temperature to yield 105 g (75.0% yield) of the desired
product.
Example 9
##STR00025##
[0140] To a solution of 1-methyl-2-pyrrolidinone 280 g, xylene 420
g and phthalic anhydride 487.2 g (3.289 mol) heated to 120.degree.
C. was added m-xylylenediamine 213.3 g (1.566 mol) over 10 minutes
during which time the temperature increased to 145.degree. C. The
solution was held at 140.degree. C. for 1 hours during which time
55.0 mL of water distillate was collected in a Dean-Stark trap. The
solution was heated to 150.degree. C. during which time an
additional 5.0 mL of water was collected and the amine value was
1.4 mg KOH/gram of sample. The resulting slurry was poured into an
aluminum tray. The cooled product was added to IPA 1000 g and the
resulting slurry was filtered and washed with IPA 200 g. The press
cake was added to IPA 1000 g and the resulting slurry was filtered
and washed with IPA 200 g. The press cake was air dried at ambient
temperature to yield 601.1 g (97.0% yield) of the desired product.
Its melting point was 243-248.degree. C. The infrared spectra was
consistent with the desired product.
Example 10--Compound 306
##STR00026##
[0141] Step 1: Methyl-(2.5-dimethyl)benzoate
##STR00027##
[0143] Into a suspension of 75 g (499 mmol) 2,5-dimethylbenzoic
acid, 103 g (748 mmol) potassium carbonate in 500 mL of DMF was
added dropwise 77.9 g (549 mmol) of iodomethane with stirring at
ambient temperature. After addition, the suspension was stirred for
additional 5 hours. The reaction mixture was then poured into water
and extracted with ethyl acetate. The organic layer was washed with
water and brine and dried over anhydrous sodium sulfate. All solids
were removed by filtration and the filtrate was concentrated to 80
g of colorless oil as product in 97.6% yield. .sup.1H NMR
(CDCl.sub.3) (300 MHz) .delta. 2.7 (s, 3H), 2.8 (s, 3H), 3.95 (s,
3H), 7.45 (s 1H), 7.51 (d, .sup.3JHCCH=7.9 Hz, 1H), 7.42 (d,
.sup.3JHCCH=7.9 Hz, 1H)
Step 2: Methyl-di(2,5-bromomethyl)benzoate
##STR00028##
[0145] Into a mixture of 80 g (487 mmol) of
methyl-(2,5-dimethyl)nitrobenzoate, 95.4 g (503 mmol) of
N-bromosuccinimide in 500 mL of carbon tetrachloride was added 121
mg (0.5 mmol) of benzoyl peroxide at 80.degree. C. Heating
continued for 16 hours and cooled to ambient temperature. The
reaction mixture was then washed with saturated sodium bicarbonate
and brine. The organic layer was dried over anhydrous sodium
sulfate. All solids were removed by filtration and the filtrate was
concentrated to a total of 152 g yellowish solid in 96.9% yield.
.sup.1H NMR (CDCl.sub.3) (300 MHz) .delta. 3.95 (s, 3H), 4.49 (s,
2H), 4.96 (s, 2H), 7.49 (s 1H), 7.54 (d, .sup.3JHCCH=7.9 Hz, 1H),
7.47 (d, 3JHCCH=7.9 Hz, 1H).
Step 3: 6-bromomethylphthalide
##STR00029##
[0147] A neat sample of 152 g (472 mmol) of
methyl-di(2,5-bromomethyl)benzoate was heated to 120.degree. C. in
a slight vacuum. The yellowish solid melted at 80.degree. C. After
16 hours of heating, the reaction mixture was cooled to ambient
temperature. Upon cooling, a total of 107 g light brown solid was
obtained as product in quantitative yield. .sup.1H NMR (CDCl.sub.3)
(300 MHz) .delta. 4.58 (s, 2H), 5.30 (s, 2H), 7.49 (s 1H), 7.54 (d,
.sup.3JHCCH=7.9 Hz, 1H), 7.47 (d, .sup.3JHCCH=7.9 Hz, 1H)
Step 4: 6-methylphthalide
##STR00030##
[0149] A total of 107 g (472 mmol) of 6-bromomethylphthalide was
dissolved in 50 mL of methanol (dioxane was also used in different
experiment). The solution was added to a parr bottle with 40 g (540
mmol) of calcium hydroxide and 2 g of 10% Pd/C. The suspension was
hydrogenated at 40 psi until no more hydrogen uptake was recorded.
All solids were filtered and filtrate was concentrated to a total
of 67 g of brown solid in 96% yield. .sup.1H NMR (CDCl.sub.3) (300
MHz) .delta. 2.53 (s, 3H), 5.30 (s, 2H), 7.49 (s 11H), 7.54 (d,
.sup.3JHCCH=7.9 Hz, 1H), 7.47 (d, .sup.3JHCCH=7.9 Hz, 1H)
Step 5:
1,3-Bis[(6-methyl-2,3-dihydro-isoindol-1-one-2-yl)methyl]benzene
[0150] A mixture of 67 g (452 mmol) 6-methylphthalide and 30.7 g
(226 mmol) xylyldiamine was heated to 180.degree. C. with a short
path distillation setup to remove water. Upon
170.degree.-180.degree. C., water was collected. After 16 hours of
heating at 180.degree. C., heating was stopped and reaction mixture
was dissolved in 200 mL of dimethylforamide. The DMF solution was
then added dropwise with stirring into 1.5 L of water to
precipitate out a total of 73 g of brownish solid. The solid was
then recrystallized with methanol to give 55 g of product in 61%
yield. .sup.1H NMR (DMSO-d.sup.6) (500 MHz) .delta. 2.54 (s, 6H),
4.29 (s, 4H), 4.79 (s, 4H), 7.20 (dd, .sup.3JHCCCH=7.6 Hz,
.sup.4JHCCCH=1.4 Hz, 2H), 7.28 (dd, .sup.3JHCCCH=7.6 Hz, 1H), 7.30
(s, 11H) 7.66 (dd, .sup.4JHCCCH=1.4 Hz, JHCCCH=0.65 Hz, 2H), 7.56
(dd, .sup.3JHCCCH=7.9 Hz, .sup.4JHCCCH=0.65 Hz, 2H'), 7.60 (dd,
.sup.3JHCCCH=7.9 Hz, .sup.4JHCCCH =1.4 Hz, 2H).
Preparation of Plaques
[0151] PET resin (Vitiva.TM., Eastman Chemical Company, Kingsport,
Tenn.) is dried in a Nissei dryer at 170.degree. C. for 4 hours
prior to use. Cobalt containing polyester (Masterbatch) (4000 ppm
Cobalt) is dried for approximately 2 hours at 350.degree. F. prior
to use.
[0152] Plaques (approximately 33.5 gram weight) are molded on
30-ton BOY 22S injection molding machine using the following
settings:
TABLE-US-00003 Barrel temperature 264.degree. C. Nozzle heater
setting 35% of the power used to heat the barrel Sprue heater set
temperature approx. 215.degree. C. Injection pressure mold 600 psi
(20 sec. of hold pressure; 15 sec. cooling time)
[0153] The mold is water cooled with process water flow rate at
approximately 0.5 LPM.
[0154] Compound 306 (19 g) is hand blended in a bucket with dried
Masterbatch (19 g) and dried PET (912 g). This mixture is poured in
the feed hopper of the BOY 22S machine.
[0155] The first 10 plaques are discarded as change-over plaques.
After the first 10 plaques are discarded, 8 plaques are collected
for oxygen scavenging evaluation. Data generated from oxygen
scavenging evaluation is shown in FIG. 3.
[0156] As seen in FIG. 3, PET plaques containing Compound 306
scavenge approximately 3.9% of oxygen after 5.5 days.
Example 11--Compound 307
1,3-Bis[(isoindole-1,3-dione-2-vi)methyl]benzene
##STR00031##
[0158] Into a suspension of 100 g (675 mmol) of phthalic anhydride,
46 g (338 mmol) of xylyldiamine and 500 mL of glacial acetic acid
was heated to 100.degree. C. After 2 hours of heating, the reaction
mixture was a clear solution. Heating continued for additional 22
hours. Upon cooling, white suspension was observed. The white solid
was filtered and recrystallized with acetic acid to give 126.6 g of
a white product in 94.5% yield. 1H NMR (DMSO-d.sub.6) (500 MHz)
.delta. 4.74 (s, 4H), 7.19 (dd, 3JHCCCH=7.7 Hz, .sup.4JHCCCH=1.5
Hz, 2H), 7.23 (s, 1H), 7.28 (dd, .sup.3JHCCCH=7.7 Hz, 1H), 7.86
(unresolved complex, 8H).
Preparation of Plaques
[0159] PET resin (Vitiva.TM., Eastman Chemical Company, Kingsport,
Tenn.) is dried in a Nissei dryer at 170.degree. C. for 4 hours
prior to use. Cobalt containing polyester (Masterbatch) (4000 ppm
Cobalt) is dried for approximately 2 hours at 350.degree. F. prior
to use.
[0160] Plaques (approximately 33.5 gram weight) are molded on
30-ton BOY 22S injection molding machine using the following
settings:
TABLE-US-00004 Barrel temperature 264.degree. C. Nozzle heater
setting 35% of the power used to heat the barrel Sprue heater set
temperature approx. 215.degree. C. Injection pressure mold 600 psi
(20 sec. of hold pressure; 15 sec. cooling time)
[0161] The mold is water cooled with process water flow rate at
approximately 0.5 LPM.
[0162] Compound 307 (38 g) is hand blended in a bucket with dried
Masterbatch (19 g) and dried PET (893 g). This mixture is poured in
the feed hopper of the BOY 22S machine.
[0163] The first 10 plaques are discarded as change-over plaques.
After the first 10 plaques are discarded, 8 plaques are collected
for oxygen scavenging evaluation. Data generated from oxygen
scavenging evaluation is shown in FIG. 5.
[0164] As seen in FIG. 5, PET plaques containing Compound 307
scavenge approximately 4% of oxygen after 25 days.
Example 12--Compound 310
##STR00032##
[0165] Step 1: Methyl-(2-methyl-6-nitro)benzoate
##STR00033##
[0167] Into a suspension of 100 g (552 mmol) of
2-methyl-6-nitrobenzoic acid, 114.4 g (828 mmol) of potassium
carbonate in 500 mL of dimethylforamide was added dropwise 86 g
(606 mmol) of iodomethane with stirring at ambient temperature.
After addition, the suspension was stirred for additional 5 hours.
The reaction mixture was then poured into water and extracted with
ethyl acetate. The organic layer was washed with water and brine
and dried over anhydrous sodium sulfate. Any solid was removed by
filtration and the filtrate was concentrated to a 105.6 g of
colorless oil as product in 98% yield. .sup.1H NMR (CDCl.sub.3)
(300 MHz) .delta. 2.7 (s, 3H), 3.95 (s, 3H), 8.01 (d,
.sup.3JHCCH=8.6 Hz, 1H), 7.62 (dd, .sup.3JHCCH=8.6 Hz,
.sup.3JHCCH=7.6 Hz, 1H), 7.8 (d, .sup.3JHCCH=7.6 Hz, 1H)
Step 2: Methyl-(2-bromomethyl-6-nitro)benzoate
##STR00034##
[0169] Into a mixture of 100 g (512 mmol) of
methyl-(2-methyl-6-nitro)benzoate, 100.2 g (563 mmol) of
N-bromosuccinimide in 500 mL of carbon tetrachloride was added 121
mg (0.5 mmol) of benzoyl peroxide at 80.degree. C. Heating
continued for 16 hours and cooled to ambient temperature. The
reaction mixture was then washed with saturated sodium bicarbonate
and brine. The organic layer was dried over anhydrous sodium
sulfate. All solids were removed by filtration and the filtrate was
concentrated to a total of 137.5 g of yellowish oil in 98% yield.
.sup.1H NMR (CDCl.sub.3) (300 MHz) .delta. 3.95 (s, 3H), 4.96 (s,
2H) 8.01 (d, .sup.3JHCCH=8.6 Hz), 7.62 (dd, .sup.3JHCCH=8.6 Hz,
3JHCCH=7.6 Hz), 7.85 (d, .sup.3JHCCH=7.6 Hz)
Step 3:
1,3-Bis[(7-nitro-2.3-dihydro-isoindol-1-one-2-yl)methyl]benzene
[0170] Into a solution of 80 g (292 mmol) of
methyl-(2-bromomethyl-6-nitro)benzoate, 19.9 g (146 mmol) of
Xylyldiamine, 32.4 g (320 mmol) triethylamine and 300 mL of
methanol was heated to reflux for 24 hours. Upon cooling, the
mixture was diluted with ethyl acetate and washed with diluted
hydrochloric acid and brine. The organic layer was dried over
anhydrous sodium sulfate. All solids were removed by filtration and
filtrate was concentrated to 61 g of a yellowish solid. Methanol
was used to recrystallize the yellowish solid to yield a total of
87 g of product in 65% yield. .sup.1H NMR (DMSO-d.sub.6) (500 MHz)
.delta. 4.47 (s, 4H), 4.72 (s, 4H), 7.22 (dd, .sup.3JHCCCH=7.5 Hz,
.sup.4JHCCCH=1.6 Hz, 2H), 7.26 (s, 1H), 7.36 (dd, .sup.3JHCCCH=7.5
Hz, 1H), 7.79 (dd, .sup.3JHCCCH=7.6 Hz, .sup.3JHCCCH=7.6 Hz, 2H),
7.84 (dd, .sup.3JHCCCH=7.6 Hz, .sup.4JHCCCH=1.0 Hz, 2H), 7.89 (dd,
.sup.3JHCCCH =7.6 Hz, .sup.4JHCCCH=1.0 Hz, 2H).
Preparation of Plaques
[0171] PET resin (Vitiva.TM., Eastman Chemical Company, Kingsport,
Tenn.) is dried in a Nissei dryer at 170.degree. C. for 4 hours
prior to use. Cobalt containing polyester (Masterbatch) (4000 ppm
Cobalt) is dried for approximately 2 hours at 350.degree. F. prior
to use.
[0172] Plaques (approximately 33.5 gram weight) are molded on
30-ton BOY 22S injection molding machine using the following
settings:
TABLE-US-00005 Barrel temperature 264.degree. C. Nozzle heater
setting 35% of the power used to heat the barrel Sprue heater set
temperature approx. 215.degree. C. Injection pressure mold 600 psi
(20 sec. of hold pressure; 15 sec. cooling time)
[0173] The mold is water cooled with process water flow rate at
approximately 0.5 LPM.
[0174] Compound 310 (23.8 g) is hand blended in a bucket with dried
Masterbatch (19 g) and dried PET (908 g). This mixture is poured in
the feed hopper of the BOY 22S machine.
[0175] The first 10 plaques are discarded as change-over plaques.
After the first 10 plaques are discarded, 8 plaques are collected
for oxygen scavenging evaluation. Data generated from oxygen
scavenging evaluation is shown in FIG. 4.
[0176] As seen in FIG. 4, PET plaques containing Compound 310
scavenge approximately 5% of oxygen after 25 days.
[0177] As those skilled in the art will appreciate, numerous
modifications and variations of the present invention are possible
in light of the above teachings. It is therefore understood that
within the scope of the appended claims, the invention may be
practiced otherwise than as specifically described herein, and the
scope of the invention is intended to encompass all such
variations.
* * * * *